Method and apparatus for forming a package of yarn



P 24, 8 D. A. E. MATTINGLY 3,402,898

METHOD AND APPARATUS FOR FORMING A PACKAGE OF YARN Filed May 6, 1965 5 Sheets-Sheet 1 wwo v ATTORNEYS Sept. 24, 1968 D. A. E. MATTINGLY 3,402,898

METHOD AND APPARATUS FOR FORMING A PACKAGE OF YARN Filed May 6, 1965 3 Sheets-Sheet 2 ATTORNEY;

Sept.

Filed 24, 1968 D. A. E. MATTINGLY Y 3,402,898

METHOD AND APPARATUS FOR FORMING A PACKAGE 0F YARN May a, 1965 s Sheets-She et 5 Fig/0 VA 06/7 Y F49. if

Vt Z0677) 77/145 INVENTOR fiN/JAtBEAffDa/fiRO/VHIMVM/ BY Wad/5+ %fl/ ATTORNEYS United States Patent 3,402,898 METHOD AND APPARATUS FOR FORMING A PACKAGE 0F YARN Denis Albert Edward Mattingly, London, England, as-

signor to The Klinger Manufacturing Company, Limited, London, England, a British company Filed May 6, 1965, Ser. No. 453,635 Claims priority, application Great Britain, May 11, 1964, 19,522/64 11 Claims. (Cl. 242-43) ABSTRACT OF THE DISCLOSURE A yarn winding method and apparatus is provided in which yarn is laid onto a take-up bobbin to form a package in which the yarn traversing speed is varied from time to time to reduce or eliminate yarn build up at the ends of the package formed.

This invention relates to methods and apparatus for laying yarns, filaments, cords and like continuous lengths of flexible material (hereinafter referred to as yarn) on a rotating bob-bin or the like to form a package.

In forming a package on a rotating bobbin the yarn can be fed to the package through a guide reciprocating relative to the bobbin so that the yarn is laid backwards and forwards on the bobbin. In this way the yarn forms on the bobbin in a type of spiral of comparatively large pitch of one hand during movement of the guide in one direction, and a spiral of similar pitch, but of opposite hand to the first spiral, during movement of the guide in the opposite direction. A package so formed can be selfsustaining without the assistance of end flanges on the bobbin.

However, when forming packages of this kind there is a tendency for yarn to build up on itself particularly at the ends of the package resulting in objectionable circumferential end ridges or uneveness.

We have found that by suitably varying the velocity of reciprocation of the yarn guide relative to the speed of rotation of the bobbin, whilst maintaining the amplitude of reciprocation of the guide constant, the length of traverse of the yarn along the bobbin can :be varied and said objectionable circumferential end ridges can be reduced or eliminated. The prevent invention stems from this finding.

According to one aspect of the present invention there is provided a method of laying yarn on a rotating bobbin to form a package comprising guiding the yarn onto the bobbin by a yarn guide reciprocating relative to the bobbin, the amplitude of this relative reciprocation being substantially constant, and varying this relative velocity of the guide relative to the peripheral speed of the package being formed on the bobbin to vary the length of some of the traverses of the yarn on the package being formed to reduce or eliminate end build-up on the package.

According to another aspect of the present invention there is provided a method of laying yarn on a rotating bobbin to form a package comprising guiding the yarn onto the bobbin by a yarn guide reciprocating relative to the bobbin, the amplitude of this relative reciprocation being substantially constant, and varying the velocity of this relative reciprocation between the yarn guide and the bob-bin to vary the length of some of the traverse of the yarn on the package being formed to reduce or eliminate end build-up on the package.

This relative velocity between the yarn guide and the bobbin can be varied by varying the rate of said relative 3,402,898 Patented Sept. 24, 1968 reciprocation whilst maintaining the peripheral speed of the package constant.

Preferably the rotating bob-bin does not move axially and the yarn guide moves to effect said relative reciprocation between the yarn guide and the bobbin.

The yarn can be guided onto the bobbin by a yarn guide reciprocating in such a manner that it moves at a uniform velocity in each direction with a substantially instantaneous change in direction at each end of reciprocation.

The rate of reciprocation of the yarn guide relative to the peripheral speed of the package may vary continuously or it may vary intermittently or spasmodically and the variation can be of the same or different magnitude at each occurrence. The rate of reciprocation of the yarn guide relative to the peripheral speed of the package is increased to shorten the length of some of the traverses of the yarn on the package.

Preferably the yarn guide reciprocates relative to and substantially parallel with the axis of rotation of the bobbin when forming a cylindrical package.

When forming packages of the yarn under particular conditions of speed of rotation and diameter of the package, and rate of reciprocation of the yarn guide, some of the spiral-like paths of the yarn having the same hand coincide, or nearly coincide, with a consequent build-up of the yarn in the form of criss-crossing spiral-like ridges which phenomenon is known as pattern or ribbon forming.

Pattern forming may be broken by varying, at the end of the package, the point around the circumference of the package at which the yarn changes direction, that is to say the point on said circumference at which the two spirals of opposite hand formed during a single reciprocation of the yarn guide are joined. It will be appreciated that when operating in accordance with the present invention the rate of reciprocation of the yarn guide relative to the peripheral speed of the package also effects a change in the position of the changeover point of the yarn at the ends of the package in addition to reducing or eliminating end build-up. Because the variation needed to reduce or eliminate end build-up on the package may be at irregular or Widely spaced intervals it may be advantageous to make an additional smaller variation during these intervals to reduce or eliminate pattern forming.

Thus the method of the present invention can include the additional step of varying the relative velocity between the yarn guide and the bobbin relative to the peripheral speed of the package to reduce or eliminate pattern forming on the package but in such a way that the length of traverse of the yarn along the package remains substantially constant.

The relative velocity of the yarn guide relative to the peripheral speed of the package may be varied continuously to reduce or eliminate pattern forming on the package. Alternatively, the relative velocity of the yarn guide relative to the peripheral speed of the package may be varied periodically to reduce or eliminate pattern forming.

When guiding yarn onto the rotating bobbin by the yarn guide reciprocating relative to the bob-bin the yarn will trail behind by a distance dependent upon the rate at which the yarn is being traversed across the bobbin, the peripheral speed of rotation of the package being formed on the bobbin, and the distance of the yarn guide from the point of contact of the yarn with the package being formed. With this arrangement the distance the guide travels in each reciprocation will be longer than the distance the yarn traverses on the package during this reciprocation of the guide. The extra distance of travel of the guide in excess of the length of traverse of the yarn on the package is approximately twice the distance by which the yarn trails behind the guide. Thus varying the distance by which the yarn trails behind the guide will vary the length of the traverse of the yarn on the package.

According to yet another aspect of the present invention there is provided :a method of forming a package of yarn comprising passing the yarn to a rotating bobbin through or over a yarn guide reciprocating relative to and substantially parallel with the axis of rotation of the bobbin such that whenever the yarn guide is acting to axially shift the point of contact of the yarn with the package being formed on the bobbin said point of contact trails behind the yarn guide with respect to the direction of movement of the guide, and periodically varying the velocity of the guide relative to the peripheral speed of the package to vary the distance by which the point of contact of the yarn with the package trails behind the yarn guide to reduce or eliminate end build-up of the package. The velocity of the guide relative to the peripheral speed of the package may be additionally varied whilst maintaining the distance by which the point of contact of the yarn with the package or bobbin trails behind the guide substantially constant to reduce or eliminate pattern forming.

Preferably the bobbin, and the package being formed thereon, is rotated by a friction drive roller engaging initially with the bobbin, and subsequently with the package being formed on the bobbin, the yarn being fed to the package such that its point of contact with the package is at the nip between the drive roller and the package. In this way changes in direction of the yarn being fed to the package do not disturb the package already formed, the yarn remaining in the position on the package at which it was fed by the yarn guide.

According to a further aspect of the present invention there is provided a method of forming a package of yarn comprising rotating the package as it is being formed and traversing the yarn backwards and forwards across the package, the velocity of traverse of the yarn across the package being intermittently or spasmodically increased, at least at the ends of the travel of the yarn in each direction, so that the yarn at such times does not traverse to the end portions of the package, whereby build-up of the yarn at the ends of the package is reduced or eliminated.

According to yet a further aspect of the present invention there is provided a method of forming a package of yarn on a rotating bobbin comprising laying the yarn backwards and forwards across the bobbin, the point from which the yarn is laid onto the bobbin oscillating over a path of substantially constant amplitude and from time to time increasing the rate of oscillation of said point to such an extent that on these occasions the yarn does not reach the end of the package being formed before the yarn is moved back across said package, and choosing the frequency of these occasions and the manner of increasing said rate of oscillation so that build-up of the yarn on the ends of the package is substantially reduced or eliminated.

The relative velocity between the yarn guide and the bobbin can be varied for at least 5% of the time taken to form the package, and can be varied at least 10% in order to vary the length of traverse of the yarn on the package.

The methods of the present invention may be employed when it is desired to form a package having barrel shaped ends, which packages can be somewhat more stable than a package with straight ends.

Increasing the rate of reciprocation of the yarn guide, and hence the rate of traverse of the yarn, relative to the peripheral speed of the package being formed will also increase the linear length of yarn being taken up by the package in a particular space of time since the path of the yarn on the package being formed will be increased by an amount proportional to the length of the package being formed. Where the yarn is subject to a positive feed before being laid upon the package an increase in tension will result between the positive feed and the package. It may be desirable, therefore, when the rate of rciprocation of the guide relative to the peripheral speed of the package is increased to any large extent, to in crease the linear feed rate of the yarn, without increasing the peripheral speed of the package being formed, in order to reduce this increase in tension.

According to a dilierent aspect of the present invention there is provided apparatus for carrying out the invention comprising a rotatable axially mounted bobbin, means for rotating said bobbin about its axis of rotation, a yarn guide, reciprocable means arranged to reciprocate said guide backwards and forwards relative to the axis of the bobbin, transmission means adapted to impart reciprocatory movement to said reciprocable means, said transmission means being adapted to vary the speed of reciprocation of said reciprocable means to reduce or eliminate build-up of yarn at the ends of the package being formed on said bobbin.

The reciprocable means can comprise a tensioned stretch of flexible inextensible material having the yarn guide secured thereto, and adapted to reciprocate relative to the length of the bobbin.

The stretch of flexible inextensible material can be supported at each end by a member which is mounted to oscillate about an axis substantially at right angles to said stretch.

The transmission means can include a follower operatively connected to and restrained to move parallel with the stretch of material, said follower engaging a peripheral slot in a cam, and means for rotating said cam about its axis of rotation. The follower can be secured directly to the stretch of material which may be a metal band. The means for rotating said cam can comprise an electric motor and the electric motor may drive the cam through a variable ratio gearbox.

Alternatively the transmission means may include means adapted to regulate the power supply to the electric motor to vary the speed thereof. The means adapted to regulate the power supply can regulate the power supply cyclically with respect to time.

According to yet a different aspect of the present invention there is provided apparatus for carrying out the invention comprising a plurality of rotatable axially mounted bobbins spaced apart in rows, means for rotating said bobbins about their axes of rotation, a plurality of yarn guides, reciprocable means adapted to reciprocate each of said guides backwards and forwards relative to the lentgh of one of said bobbins, transmission means adapted to impart reciprocatory movement to said reciprocable means, said transmission means being adapted to vary the speed of reciprocation of said reciprocable means to reduce or eliminate build-up of the yarn at the ends of the package being formed on said bobbin.

The reciprocable means can comprise a pulley or like member mounted at each end of the apparatus, two parallel stretches of flexible inextensible material stretch passing over said pulleys and extending under tension between said pulleys on opposite sides of their axes of rotation, the guide members being secured to and spaced apart along at least one of the stretches of material at distances corresponding to the spacing apart of the bobbins. Guides may be secured to both of the stretches when the bobbins are arranged in two rows along the machine. The stretches of material can comprise a single continuous stretch of material.

By way of example, embodiments of the present invention will now be described with reference to the accompanying diagrammatic drawings, in which:

FIGURE 1 shows schematically one form of apparatus,

which may be used to carry out the present invention;

FIGURE 2 is an end elevation of part of the apparatus in the direction of arrow II in FIGURE 1;

FIGURE 3 is a schematic view showing yarn being wound upon a bobbin;

FIGURE 4 is a view similar to FIGURE 3;

FIGURE 5 is a plan view of a package having barrel shaped ends;

FIGURE 6 is a graph illustrating the velocity of the yarn guide being constantly varied with respect to time;

FIGURES 7, 8 and 9 are graphs illustrating the velocity of the yarn guide being varied intermittently with respect to time;

FIGURES l and 11 are graphs illustrating the the velocity of the yarn guide being constantly varied with respect to time to reduce or eliminate pattern forming;

FIGURE 12 is a graph illustrating the velocity of the yarn guide being constantly varied with respect to time to reduce or eliminate pattern forming, and intermittently varied to reduce or eliminate end buildup and FIGURES 13 and 14 are graphs illustrating the velocity of the yarn guide being intermittently varied with respect to time to reduce or eliminate pattern forming, and intermittently varied to reduce or eliminate end build-up.

Referring to FIGURE 1, a guide 1 is mounted on and secured to a flexible inextensible steel band 2 passing over and clamped at 20 to pulleys 3 and 4 which are free to rotate on spindles 5 and 6 respectively. That portion of the circumference of the pulleys which in operation does not come into contact with the band 2 is cut away to reduce the inertia of the reciprocating parts: one or both pulleys may be adjustable to increase or decrease the distance between the spindles 5 and 6 so as to tension the band 2. Secured to the steel band at any convenient point is a follower 7 restrained to move parallel to the band by a pair of parallel guide rods 8 (only one of which can be seen). The follower 7 engages a slot 9 formed within an upstanding projection on the periphery of a cam 10 which is rotatably mounted on supports 11 and is rotated by a chain drive 21 connecting a sprocket 12 to a variable speed gearbox 17 which is driven by an electric motor 18.

Rotation of the cam 10 causes the follower 7 to reciprocate along the guide rods 8, the band 2 and guide 1 reciprocating with the follower, and the pulleys 3 and 4 oscillating about their respective spindles 5 and 6. The cam slot 9 is so proportioned as to apply constant velocity reciprocation to the band 2 as described in British patent specification No. 885,473.

A package 13 being formed on a bobbin 16 is rotated at a constant peripheral speed by a drive roller 14 in the normal manner, the roller 14 being driven by any convenient transmission.

British patent specification No. 885,473 more fully de scribes other details of the apparatus described above together with alternative arrangements therefor.

The above arrangement is suitable for use in an apparatus for false twisting a plurality of yarns simultaneously wherein a plurality of bobbins are spaced apart in rows along the machine. In such machines additional yarn guides can be secured to the band 2 at intervals corresponding to the spacing apart of the bobbins, the bobbins in any one row being substantially co-axial and the band 2 being parallel with the axes of the bobbins. Further guides may be secured to the second parallel stretch of the band, these guides being arranged to guide yarn onto a second similar row of bobbins. Further rows of bobbins may be added as is convenient by including further arrangements as described above.

As shown in FIGURE 3, the yarn 19 passes through a stationary guide 15 and is laid on the bobbin 16 to form the package 13. In order to spread the yarn across the width of the package, the yarn 19 is guided backwards and forwards across the package being formed by the reciprocating guide 1, the yarn being laid in the form of a type of spiral having a comparatively large pitch during movement of the guide in one direction and a spiral of similar pitch but opposite hand during movement of the guide in the opposite direction, the pitch of the spirals increasing as the package builds up. The package thereby formed is self-sustaining without the assistance of shoulders on the bobbin 16.

As shown in FIGURE 2 the yarn 19 contacts the package 13 being formed on the bobbin 16 at the nip between the package 13 and the driving roller 14, and the guide 1 is disposed at a distance a from the centre of this nip.

In operation, the yarn trails behind the guide 1 forming an angle X with the axis of the package, this angle remaining substantially constant for a given velocity of the guide 1. The angle X is also dependent upon the distance a but as the yarn is fed onto the package to the nip between the package and the driving roller as shown in FIGURE 2, no substantial variation in a course due to growth of the package if it is arranged that growth of the package does not substantially alter the point of contact of the package and the driving roller 14. The angle X is also dependent upon the peripheral speed of the package.

Because the yarn trails behind the guide 1, the length of traverse of the yarn on the package, and so the length of the package itself, is less than the distance through which the guide 1 reciprocates.

One factor believed to contribute towards build-up of yarn at the ends of the package, when the yarn is being fed to the package under tension, is that at the moment that the yarn guide changes its direction of movement there is a sudden lessening of the tension in the yarn, the tension being restored when the yarn guide starts pulling the yarn in the opposite direction. This lessening of the tension allows the yarn to bulk as it is laid at the ends of the package with the result that the ends of the package grow in diameter at a rate greater than the centre portion of the package.

Another factor contributing towards the build-up of yarn at the ends of the package is that when the yarn guide changes its direction of movement, there is a time lag between when the guide ceases to pull the yarn in one direction and when it starts to pull the yarn in the opposite direction. During this time lag the yarn is not traversed along the package, the yarn being laid in substantially the same position on the package, with a consequent build-up of yarn at that position.

FIGURE 4 shows the effect of increasing the velocity of the reciprocating guide 1. Increasing the velocity has increased the angle X to a new angle Y. As illustrated at b the guide is at one extreme of its travel and because of the larger angle Y the length of traverse of the yarn on the package is shortened, with the effect that yarn does not reach the zone at which end build-up usually occurs. As a result of this increase in velocity of the yarn guide, the yarn changes direction on the package (to start travellingtowards the other end of the package) at a zone away from the end of the package.

In order that the guide 1 may exercise control over the path the yarn upon the package, it is desirable that distance a is not too large, nor so small as to reduce to an ineffectual size the effect that the change in the angle X to Y has on shortening the length of traverse of the yarn on the package. Distance 11 can conveniently be between inch and 3 inches and preferably between inch and 1%. inches.

Increasing and decreasing the velocity of the guide, will, therefore, decrease and increase respectively the length of traverse of the yarn on the package, and end build-up may be spread over a greater portion of the ends of the package With a corresponding reduction or elimination of its effect.

As explained above, one factor that constributes towards end build-up is the time lag involved when the guide 1 changes direction, a small delay occuring before the guide has travelled back along its path to start pulling the yarn in the opposite direction, As shown in FIG- URE 4 the guide must reach position (shown in broken lines) before it will again exercise full control over the yarn. Although angle Y is greater than angle X, and hence the distance between positions 5 and c is greater with angle Y than with angle X, the increase in velocity of the guide at least cancels out the effect of this increased distance and increased build-up on the package from this cause is not apparent.

It is found when reciprocating the guide 1 at a constant velocity that there is at times a tendency for the yarn to build up on itself forming a pattern of criss-crossing spiral ridges. This pattern or ribbon forming can be reduced or eliminated by constantly varying the velocity of the guide so that the point on the bobbin at which the yarn changes direction is moved around the periphery of the package, the variation in velocity required for this purpose is insumcient to effectively alter the length of the traverse of the yarn on the package. Examples of constant variations in velocity to effect pattern breaking are illustrated diagrammatically in FIGURES l0 and ll.

When the velocity of the guide is varied within wider limits, as shown in FIGURE 6, such as are necessary to effect a variation in the length of traverse of the yarn on the package, it will be appreciated that not only is end build-up reduced or eliminated but pattern forming is also reduced or eliminated.

The increase in velocity necessary to reduce or eliminate end build-up, may only be required intermittently, as shown in FIGURE 7, and the increase may be of dif fering magnitude at each occurrence; FIGURE 8 illustrates an intermittent increase in velocity to reduce or eliminate end buildup of yarn on the package in which the increases in velocity are not all of equal magnitude. As shown in FIGURE 9 the velocity may be varied to a new value, sufiicient to effect a variation in the length of traverse of the yarn on the package, and maintained constant at this value for a period of time before varying the velocity again.

In any of these examples pattern forming may take place during the period that the velocity of hte guide remains constant. If pattern forming during these periods reaches an objectionable level it can be overcome by superimposing a variation in velocity, sufiicient to effect pattern breaking, upon the constant velocity of these periods. An example of this is illustrated in FIGURE 12 which shows a combination of the velocity changes shown in FIGURE 7 and FIGURE 10, the resultant velocity variation effectively preventing pattern forming and end build-up.

Alternatively, the increase required to reduce or eliminate end build-up as illustrated by FIGURE 7 may be superimposed upon an intermittent or spasmodic increase which effects pattern breaking to give a compound velocity variation as shown in FIGURE 13.

The variations required to reduce or eliminate end build-up or pattern forming may each be continuous or intermittent and any form of intermittent variation to reduce or eliminate end build-up may be combined with a continuous or intermittent variation to effect pattern breaking. An intermittent variation may be at regular or irregular intervals. The amount of variation may be the same or different at each occurrence and the manner in which each variation is made with respect to time may vary. For example the variation may be sinusoidal as illustrated in FIGURE 11 or may be made at a constant rate of increase and decrease as shown for simplicity in FIGURES 6 to and 12 to 14. Again, the variation required to effect a variation in the length of traverse of the yarn on the package to reduce or eliminate end buildup may be such that the length of traverse of the yarn onthe package is altered and maintained at this new length for a period of time before being altered again, either to a new length or to the original length, as shown in FIGURE 9. FIGURE 14 illustrates a combination of the velocity change shown in FIGURE 9 with a similar velocity change of lesser magnitude superimposed to etIect pattern breaking.

The invention can also be employed to form a package having barrel-shaped ends as shown in FIGURE 5 by increasing, either progressively or in steps, the velocity of the yarn guide in order to shorten the length of traverse of the yarn on the package as the package grows in diameter.

Any convenient means can be adapted for providing the desired variations in the velocity of the guide 1. When using the apparatus of FIGURE 1 the speed of the electric motor 18 may be maintained constant and the speed of rotation of the cam varied by means of the variable speed gearbox 17.

With this arrangement a single electric motor may be used to drive both the driving roller 14 and the cam It), the driving roller 14 which is required to rotate at a constant speed, being driven from a constant speed power take off and the transmission to the cam 10 embodying the variable speed gear box.

Alternatively the power supplied to the electric motor 18 may be varied to vary the speed thereof. Any known means, such as a variable resistance or an oscillator controlled build-up and let down circuit can be adapted for this purpose, the latter means being particularly suitable since it can b adapted to automatically vary the power supplied to the electric motor in a particular manner with respect to time.

Preferably the speed of the guide is arranged to vary at intervals of between A. and 5 minutes, for example 2 minutes, and may conveniently be arranged to vary through a cycle of variations within such a period.

Or again, the means can comprise a plurality of resistive circuits, either or" fixed value or adapted to be set to a pre-determined value, each circuit including a switch adapted to be operated by a cam such that various circuits or combinations of circuits having different resistive values may be brought into operation to vary the power supplied to the motor. A single cam may be provided for each circuit or one cam may be adapted to operate the switches in several circuits; when a number of cams are provided they can rotate at the same or different speeds as each other. The resistive circuits can be included in the power supply to the motor or can be adapted to function through an amplifier to control the power supply. The cam or cams determin the frequency and intervals at which the variations are made and the values of the resistive circuits determine the magnitude of the variations. By arranging to vary the speeds and/or shapes of the cams and the resistive values of the circuits various sequences of velocity change of the yarn guide such as are shown in FIGURES 6 to 14 can be obtained.

The apparatus as described was used to form a package at a linear rate of feed of yarn of 350 feet per minute. The yarn guide was arranged to reciprocate through a distance of 6 inches and the distance a (FIGURE 2) was 1 inch. With the yarn guide reciprocating at 60 complete reciprocations per minute, the length of traverse of the yarn on the package was 5.9 inches. Increasing the velocity of the guide so that it made complete reciprocations per minute, although the amplitude of reciprocation of the guide remained constant, the length of traverse of the yarn on the package was 5.4 inches. Further increasing the rate of reciprocation to complete reciprocations per minute, the amplitude of reciprocation of the guide still remaining constant, resulted in a length of traverse of the yarn on the package of 5.2 inches.

It was found that end build-up of yarn on the package could be er'iiciently reduced or eliminated when the variation in velocity of the yarn guide sulficient to alter the length of traverse of the yarn on the package occurs for between 5% to 25% for example 10% of the time taken to form the package, although in some circumstances 9 the variations could be for up to at least 50% of this time.

The percentage variation in the velocity of the yarn guide from the normal velocity in order to vary the length of traverse of the yarn on the package was found to be at least 10%, and preferably or more. Small changes in the velocity of the yarn guide, whilst theoretically altering the length of traverse of the yarn upon the package, do not in practice cause such a change in length, the yarn tending to follow the previously laid turns on the package. These small changes are, however, effective in changing the relationship between the rotation of the package and the reciprocation of the yarn guide so as to effect ribbon breaking.

What is claimed is:

1. A method of winding yarn on a bobbin to form a package comprising the steps of:

(a) rotating the bobbin to wind yarn thereon;

(b) traversing the yarn axially of the bobbin to form a package defined by successive layers of yarn; and

(c) increasing and decreasing the speed of the traverse of the yarn relative to the peripheral speed of the package so as to vary the length of the traverse of the yarn in certain layers on the bobbin, whereby build-up of the yarn at the ends of the package is reduced.

2. A method of winding yarn on a bobbin to form a package comprising the steps of: I

(a) rotating the bobbin to wind yarn thereon;

(b) traversing the yarn substantially axially of the bobbin to form a package defined by successive traverses; and

(c) varying the absolute traverse speed of the yarn to vary the traverse speed relative to the peripheral speed of the package so as to vary the length of certain traverses of yarn laid onto one another Whereby build-up of yarn at the ends of the package is reduced.

3. A method of winding yarn according to claim 2, comprising during the steps (b) and (c) traversing the yarn axially of the bobbin and maintaining the bobbin substantially stationary in an axial direction.

4. A method according to claim 2 comprising varying the absolute speed of traverse by at least 10% at each occurrence.

5. A method according to claim 2 comprising varying the speed absolute speed of traverse for at least 5% of the time taken to form the package.

:6. A method according to claim 4, comprising varying 10 the speed of traverse for at least 5% of the time taken to form a package.

7. A method according to claim 1, in which said traversing is with a constant amplitude at a predetermined distance from the point of laying the yarn onto the bobbin.

8. Apparatus for forming a package, comprising means for supporting a bobbin for rotation about its axis, means for rotating the bobbin, a yarn traversing guide arranged at a predetermined distance from the bobbin to move axially of and adjacent the bobbin to guide yarn onto the bobbin to form the package, means for causing traversing movement of the yarn traversing guide, and control means for increasing and decreasing the speed of the yarn traversing guide and the peripheral speed of the package relative to one another so as to vary the lengths of certain traverses of the yarn laid onto the package.

9. Apparatus according to claim 8, in which the control means includes auxiliary control means arranged to vary the speed of the yarn traversing guide relative to the peripheral speed in the package.

10. Apparatus according to claim 8, in which said means for causing traversing movement of the yarn traversing guide causes said movement to be of constant amplitude.

11. Apparatus for forming a package, comprising means for supporting a bobbin for rotation about its axis, means for rotating the bobbin, a yarn traversing guide arranged at a predetermined distance from the bobbin to move axially of and adjacent the bobbin to guide yarn onto the bobbin to form the package, means for causing traversing movement of the yarn traversing guide, and control means for varying the speed of the yarn traversing guide and the peripheral speed of the package relative to one another by varying the absolute speed of the yarn traversing guide, so as to vary the lengths of certain traverses of the yarn laid onto the package.

References Cited UNITED STATES PATENTS 954,344 4/1910 Rhoades 242-178 1,957,979 5/ 1934 Richter 24243.1 2,608,354 8/1952 Whittaker 242-43 2,649,254 8/ 1953 Balthrop 24243 2,763,824 9/ 1956' Bacheler 24218.1 X 2,848,173 8/1958 Hebberling 242-43 3,235,191 2/1966 Engelman et a1. 242-18.1

STANLEY N. GILREATH, Primary Examiner. 

